Concrete placement

ABSTRACT

A system is provided for delivering a settable concrete mixture to a placement point which includes a gas-solids delivery system for transporting dry cementitious material and suitable aggregate to a water addition zone, and thereafter it carries the cementitious material and water to a deceleration and mixing zone having its outlet positioned over the placement point. The deceleration and mixing zone causes the gas-solids stream to agitate as it decelerates and thereby thoroughly blends the concrete constituents to form a settable mixture, which drops from the opening on the predetermined concrete placement point.

United States Patent [1 1 Anderson et al.

[ Dec. 18, 1973 CONCRETE PLACEMENT [75] Inventors: Reg A. Anderson,Dallas; Ronald W. Chandler, Richardson; Frederick N. Mueller, Dallas;Norbert L. Osborn, Plano, all of Tex.

[73] Assignee: Tetradyne Corporation, Dallas, Tex.

[22] Filed: June 7, 1971 [21] Appl. No.: 150,542

[52] US. Cl 259/147, 259/151, 259/161 [51] Int. Cl. B28c 5/06 [58] Fieldof Search 259/147, 151, 4,

[56] References Cited UNITED STATES PATENTS 1,731,953 10/1929 Thomson259/147 MacRae 259/147 2,653,733 9/1953 Rudd et al. 137/604 X PrimaryExaminer-Harvey G. Hornsby Assistant ExaminerPhilip R. CoeAttorney-Richards, Harris & Hubbard 57] ABSTRACT A system is providedfor delivering a settable concrete mixture to a placement point whichincludes a gassolids delivery system for transporting dry cementitiousmaterial and suitable aggregate to a water addition zone, and thereafterit carries the cementitious material and water to a deceleration andmixing zone having its outlet positioned over the placement point. Thedeceleration and mixing zone causes the gassolids stream to agitate asit decelerates and thereby v thoroughly blends the concrete constituentsto form a settable mixture, which drops from the opening on thepredetermined concrete placement point.

10 Claims, 10 Drawing Figures EATENTEDHEC 18 ms 3.779.519 SHEET 10$ 4 l02/ 2O 2/ IO INVENTORSI REG A. ANDERSON RONALD W CHANDLER FREDERICK NMUELLER NORBE RT L. OSBORN MWMW W ATTORNEYS FIG.6

FMENTEDBEC 1 a 1915 SHEET 2 [IF 4 SHEET 3 0f 4 PATENTED DEC 1 8 I973 mat WW 0 5 Wm W A A G E R RONALD W CHANDLER FREDERICK N. MUELLER NORBE RTL. OSBORN 4, %M/@Mm ATTORNEYS PATENTED um: 18 ms SHEET & 0F 4 FIG. /0

INVENTORSZ REG A. ANDERSON RONALD W CHANDLER FREDERICK N. MUELLERNORBERT L. OSBORN W M ,i imc ATTORNEYS CONCRETE PLACEMENT This inventionrelates to concrete placement. In another aspect, this invention relatesto a novel method for admixing and delivering a settable, cementitiousmixture to a placement point.

Various methods have been devised for delivering a settable cementitiousmixture to a desired placement point. It is customary practice toinitially admix the proper proportions of Portland cement, aggregate andwater in a conventional mixing device such as a mixing truck whichprovides a constant agitating motion to the mixture until it isultimately delivered to the placement point.

If the placement point is readily accessible, the truck can merely bepositioned adjacent the point and the cement delivered directly theretoin mixed form from a trough attached to the mixer. However, when theplacement point is inaccessible to the truck, either manual labor orspecialized equipment is necessary to transport the settable mixturefrom the truck to the placement point. Examples of such specializedcement transporting and placing machines which utilize hoppers inconjunction with endless. belts for transporting the settable mixtureare disclosed in U.S. Pat. No. 3,185,450 and U.S. Pat. No. 3,367,636.Most such conventional equipment which is utilized for admixing anddelivering a mixed cement material to a placement point has the generaldisadvantages of being (I) very expensive, cumbersome and difficult tomaintain, and (2) unsuitable for delivering small quantities'of mixedcement because large quantities of the settable cement material must bepremixed in the vehicle.

Some advances have been made in transporting water-cement mixtures inairstreams such as disclosed in U.S. Pat. No. 1,534,008. However, thistechnique requires complicated equipment which initially admixes orsuspends a water-cement mixture in an airstream, which is transported toa mixing zone wherein further amounts of water are added thereto. Someother techniques which utilize an air delivery stream include the cementgunning systems which deliver a mixture of cementitious material underpressure from a nozzle. Such systems are nonnally utilized to formvertical walls and the like from a cementitious mixture containing avery fine aggregateand are not adaptable to operations for deliveringcement mixtures containing the larger aggregates. An example of such asysternis disclosed in U.S. Pat. No. 1,953,091.

Therefore, a system is needed which is capable of delivering either alarge or a very small quantity of a cementitious mixture to placementpoints without the necessity of premixing the mixture. In addition, asystem is needed which can deliver settable cement mixtures to placementpoints which are inaccessible to conventional mixing trucks and othercement mixing equipment.

Thus, one object of this invention is to provide a novel method formixing'and delivering a cementitious mixture to a predetermined point.

According to the invention, a method is provided for suspending asettable cement mixture in an airstream and thereafter transmitting thesuspended mixture to a deceleration and mixing zone wherein theconstituents of the cement mixture are thoroughly blended asthey aredecelerated andthen allowed to drop therefrom upon the desired placementpoint.

. of this invention;

According to one embodiment of this invention, a method is'provided fordelivering a settable cement mixture to a placement point by initiallysuspending dry cement materials including cement and aggregate in anairstream which transports such materials to a water mixing zone whereinthe proper amount of water is added to the cement to cause hydrationthereof, and thereafter passes the resulting mixture into a decelerationand mixing zone wherein the constituents are thoroughly bended, such asby rotating motion wherein the kinetic energy in the constituents isutilized to cause mixing and result in the deceleration thereof, afterwhich the blended constituents are allowed to drop into place at thecement placement point.

According to a preferred embodiment of this invention, a method isprovided for delivering predetermined quantities of cement and aggregateto an airstream in a conduit which contains an annular water deliverynozzle, which in turn provides a constant spray of water to theairstream, to thereby impart the desired quantity of water into theairstream, the conduit communicating from the nozzle to the interior ofan enclosed deceleration and mixing chamber, having an outlet at thelower end thereof and adapted to impart rotating motion to thefluid-solids stream delivered by the conduit to thereby provideinitimate blending of the constituents of the stream as they decelerateand then drop from said outlet.

This invention can be more easily understood from a study of thedrawings in which:

FIG. 1 is a schematic illustration of the concrete placement system ofthis invention;

FIG. 2 is a sectional view of the water injector illustrated in FIG. 1;

FIG. 3 is an elevational view, partly in section of a preferred concretemixing and delivery unit of this invention;

FIG. 4 is a sectional view along lines 44 of FIG. 3;

FIG. 5 is a sectional view illustrating a modification of the apparatusof FIG. 3;

FIG. 6 is a sectional view of another concrete mixing and delivery unitwhich can be used within the scope FIG. 7 is a perspective view of thepreferred cement delivery apparatus of this invention;

FIG. 8 is a side elevational view partly in section of the apparatus ofFIG. 7; Y

FIG. 9 is an end elevational view, partly in section of the apparatus ofFIG. 8; and

FIG. 10 is a schematic view of the delivery system of the apparatus ofFIG. 7.

Now referring to the drawings, and particularly to FIG. 1, a schematicview is depicted, illustrating the concrete placement system of thesubject invention. As illustrated, conduit 10 communicates between theoutlet of air supply unit 11 and the inlet of concrete mixing anddelivery unit 12. Solids feeder unit 13 operatively communicates withconduit 10, and can be any suitable mechanism for injecting solids intoan airstream. Solids feeder unit 13 generally comprises feeder bin 14which operatively communicates with an injector mechanism 15 which canbe any suitable mechanism known in the art, such as a rotary air lockfeeder, screw conveyor, or the like, which is-adapted to inject solidsmaterial into a flowing airstreamoAs is set forth below in relation toFIGS. 7-10, solids feeder unit l3 can comprise one or more injectormechanism 15, each equipped with a feeder bin 14 for delivering cementmaterial, such as Portland cement together with aggregate into anairstream flowing through a conduit.

Water injector 16 operatively communicates with conduit 10, preferablyat a point adjacent the inlet of concrete mixing and delivery unit 12,and functions to uniformly inject water into the gas-solids streamflowing through conduit 10. Water delivery conduit 17 operativelycommunicates with water injector 16.

Concrete mixing and delivery unit 12 carries an outlet 18 at its lowerend opposite the upper enclosed end 19 and comprises an enclosed chamberhaving generally continuous sidewalls and is adapted to receive thefluid-solids stream emitted from conduit and thoroughly blend theconstituents therewithin while decelerating them so that they dropdownwardly from outlet 18. For example, in the operation of the deviceas illustrated in FIG. 1, the fluid-solids stream which is emitted fromconduit 10 enters concrete mixing and delivery unit 12 tangentially blowthe upper enclosed end 19 and thereby rotates within unit 12 and followsa generally spiral path downwardly therein until the material drops fromoutlet 18. The rotating motion within concrete mixing and delivery unit12 not only functions to thoroughly blend the cementitious constituentsbut also functions to decelerate them in a manner so that they will dropfrom outlet 18 preferably at their gravitational velocity." Bygravitational velocity it is herein meant a velocity which issubstantially the same as that solely attributed to the acceleration ofgravity acting upon the mixture which is blended within unit 12.

In operation of the system as illustrated in FIG. 1, a gaseous stream,preferably an airstream is induced by air supply unit 11 within conduit10 at a sufficient solids entraining velocity (a velocity sufficient toentrain solids emitted from solids feeder unit 13) and carries them toconcrete mixing and delivery unit 12. Thereafter, a dry cementitiousmaterial, for example, Portland cement and a suitable aggregate materialis delivered to the interior of conduit 10 at a desired rate by theaction of solids feeder unit 13. Water injector 16 functions to impart auniform spray of water to the interior of conduit 10, preferably anannular spray of water at a desired uniform rate in relation to theamount of hydratable cement material flowing therethrough to yield afluid-solids stream which tangentially enters the concrete mixing anddelivery unit 12 and rotates therewithin along a spiral path towardoutlet 18. This shearing action not only decelerates the constituentsbut causes a thorough blending thereof such that when they fall fromoutlet 18, they are adequately mixed into a cementitious blend whichwill uniformly set to yield a hardened concrete material.

Typical operating parameters which can be utilized in the scope of thisinvention include utilization of an air velocity water injector conduit10 of from about 75 to about 150 feet per second which will carry thecementitious solids in a weight ratio of solids to air of about from 5:lto about 20:1. The cementitious materials can comprise from 3 to I00weight percent Portland cement and from 97 to 0 weight percent of anysuitable size of aggregate (for example sand and/or gravel). Inaddition, water can be uniformly injected into the fluidsolids streampassing through water injector 16 at a rate to produce about 3 to about9 gallons per 94 lbs. cement. With such an airstream, a concrete mixingand delivery unit of generally a frusto-conical shape, having atangential inlet and having an average internal diameter of l to 3 feetand being 2 to 4 feet in length, depending on the delivery rate, can beutilized to thoroughly admix such streams, decelerate them tosubstantially their gravitational velocity and deposit them as they fallfrom outlet 18.

In order to assure that a constant velocity of water will be uniformlyinjected into fluid-solids stream passing through waterinjector 16, itis preferred that water injector 16 have a configuration as illustratedin FIG. 2, which is a cross sectional view of the preferred water Iinjector 16. As illustrated, water injector 16 comprises a tubularhousing 20 which is operatively connected within conduit 10 via suitablecouplings 21. A water manifold 22 extends around the internal peripheryof the middle of housing 20 and communicates with water inlet 23, whichin turn operatively communicates with water supply conduit 17. Recesses24 extend around the sides of water manifold 22 and align with recesses25 of locking rings 26 which fit within the interior of tubular housing20. Matching recesses 24 and 25 retain a pair of opposed annular sealingelements 27. Each sealing element 27 comprises an annular body having acylindrical seating section 27a, which carries a continuous inturnedresilient sealing lip 27b. The sealing lips 27b of the opposed sealingelements 27 preferably decrease in thickness toward inturned tip thereofas illustrated in the drawing. Thus, as each sealing element 27 isfitted within the matching opposed recesses 24 and 25, the tips of thesealing lips 27b of each sealing element 27 engage in sealingrelationship so that the interior of water manifold 22 is fullyenclosed. Sealing elements 27 are made of a resilient material so thatthe sealing lips 27b thereof will yield inwardly (of sealing element 27)to a predetermined pressure within water manifold 22. Thus, at anypredetermined pressure one can be assured that a constant velocity ofwater will flow through the opposed sealing .lips 27b uniformly into theinterior of housing 20. Sealing elements 27 can be made of any suitableresilient material, such as natural or synthetic rubber, nylon, springsteel, and the like.

As explained above, concrete mixing and delivery unit 12 is providedwith means for imparting a decelerating and turbulent mixing action tothe fluid-solids stream delivered into the inlet thereof, to therebyimpart blending action to the constituents of said stream whiledecelerating the constituents to approximately their gravitationalvelocity. Concrete mixing and delivery unit 12 is shown as an enclosedchamber comprising an upper cylindrical section joined to a lowerfrusto-conical section having outlet 18 at its apex. In addition thechamber has a tangential inlet in the upper portion thereof withnobaffles in either the upper cylindrical section or the lowerfrusto-conical section. FIGS. 3-6 set forth other embodiments of theconcrete mixing and delivery unit which can be used in the scope of thisinvention.

FIG. 3 is an elevational view partly insection of a preferred concretemixing and delivery unit of this invention designated as unit 12a. Asshown, concrete mixing and delivery unit 12a comprises a top cylindricalsection 30, which is enclosed at its upper end and carries tangentialinlet 31 in operative communication therewith and a lower frusto-conicalsection 40 which communicates with the bottom of cylindrical section 30.A series of flow control baffles is positioned in the flow path of thefluid-solids stream emitted by tangential inlet 31. The stream normallywill travel in a spiral path downwardly in concrete mixing and deliveryunit 12a. The position of the flow control baffles is illustrated inFIG. 3 and FIG. 4, which is a sectional view taken along lines 44 ofFIG. 3. As illustrated, baffle 32 is generally a curved blade positionedat the outlet of tangential inlet 31 within cylindrical section 30.Baffle 32 is suspended therewithin the support members 33, which extendfrom the walls of cylindrical unit 30. Baffle 34 is positioned in thespiral flow path at a point further around the circumference ofcylindrical unit 30 (approximately 90 from baffle 32). Baffle 34 isgenerally arcuately shaped and positioned to deflect the fluid-solidsstream outwardly toward the periphery of cylindrical unit 30. Baffle 34is suspended within the interior of cylindrical unit 30 by supportmembers 35. As shown, frusto-conical section 40 which operativelycommunicates at its wider end with the lower portion of cylindricalsection 30 converges to a narrower outlet 18a. Baffle 36 is generallyarcuately shaped and is positioned approximately 180 from baffle 32.Baffle 36 is suspended from the sides of cylindrical section 30 andfrusto-conical section 40 by support members 37, and functions to dividethe fluid-solids stream to enhance the mixing action. The actions ofbaffle 32, 34, and 36 within the concrete mixing and delivery unit 12awill thereby function to direct the fluid-solids stream in a generallyspiral downwardpath toward outlet 18a as shown by flow arrows 38 andcause deceleration and blending of the components thereof.

Another embodiment of the concrete mixing and delivery unit of thisinvention is setforth in the sectional view of unit 12b as illustratedin FIG. 5. This unit 12b is basically the same unit as the concretemixing and delivery unit 12a except it does not contain baffles 32, 34and 36 but contains a single spiral baffle 39. Baffle 39 is a twistedunitary metal piece placed within tangential inlet 31 and imparts atwisting motion of the fluid-solids stream introduced into the interiorof the concrete mixing and delivery unit 12b, as illustrated by flowarrows 41. Once inside the unit, the fluid-solids stream will passgenerally toward the outlet thereof in a spiral path.

A further but lesser preferred embodiment of the concrete mixing anddelivery unit of this invention is illustrated in FIG. 6 as unit 120.FIG. 6 generally comprises an elongated enclosed body comprising anupper cylindrical section 42 operatively communicating with lowerfrusto-conical section 43. Fluid-solids inlet 45 communicates with theupper portion thereof and delivers the fluid-solids stream to theinterior thereof. Rotor 46 is rotatably mounted through the upperportion of unit 12c and carries a pair of paddles 47 extending therefromby support members 48. Paddles 47 are positioned adjacent the sidewallsof the upper cylindrical section 42. Motor 49 functions to continuouslyrotate rotor spindle 46 and paddles 47 around the interior ofcylindrical section 42 and agitate the fluid-solids material as itbecomes deposited therein from fluid-solids inlet 45. The resultingagitated and decelerated material drops from outlet 18c onto a placementpoint.

Referring again to FIG. 1, air supply unit 12 together with solidsfeeder unit 13 and water supply for water delivery conduit 17 arepreferably contained in a single unit. The unit can be a stationaryunit, a towed vehicle, or preferably a truck such as illustrated inFIGS. 7-10.

Now referring to FIG. 7, a preferred embodiment of this invention isillustrated in perspective. As shown, truck 70 contains an air supplyunit, and concrete mixing and delivery unit 12 communicating withconduit 10, and a water supply unit communicating with water deliveryconduit 17, which are both carried by extendable boom 71. Concretemixing and delivery unit 12 can be the units 12, 12a, 12b or 120 whichare illustrated in FIGS. 1, 3, 5, and 6, respectively, and isoperatively attached to delivery conduit 10.

Extendable boom 71 can be any suitable extendable boom known in the art,such as the three section boom comprising sections 72, 73, and 74, whichare operated by hydraulic cylinders 75 and 76; 77 and 78, respectively,which are controlled by a conventional hydraulic system operable by thetruck driver.

The body of truck 70 is equipped with suitable material loading meansincluding cement loading port 79; aggregate loading openings 80 and 81,and water loading port 82.

Concrete mixing and delivery unit 12 includes handles84 adapted formanual manipulation by a workman to thereby hold unit 12 above theconcrete placement point. In addition, eye 85 is carried on a topportion of unit 112 to cooperate with hook 86 on the end of section 74of extendable boom 71 to thereby allow concrete mixing and delivery unit12 to be remotely positioned over the desired placement point by theaction of boom 71.

Referring to FIGS. 8-10, the concrete delivery system carried by truckis shown in detail. As illustrated in FIG. 9, cement loading port 79operatively communicates with cement hopper 90; aggregate loadingopening comprises the upper portion of sand hopper 91; aggregate loadingopening 81 comprises the upper portion of rock hopper bin 92; and waterloading port 82 operatively communicates with water tank 93.

Cement hopper comprises a conventionally shaped cement hopper whereinthe sidewalls converge to the bottom section 94 which is narrower andsmaller in cross-sectional area than the upper inlet portion of hopper90. The bottom section 94 of cement hopper 90 opens directly into feederunit 95. Feeder unit 95 comprises an enclosed vane-type feeder whichincludes several vanes 96 mounted upon a spindle 97 which rotates withinan enclosed housing which in turn communicates between cement hopper 90and cement receiving manifold 98. A suitable such feeder unit includesthe rotary air lock feeder unit sold under'the trademark of ROTO-FLO byWm. W. Meyer & Sons, Inc., of Skokie, Ill. Thus, the speed at whichspindle 97 rotates will control the amount of cement which is deliveredto cement receiving manifold 98. Thegspeed control for spindle 97 willbe discussed in detail below.

Sand hopper 91 and rock hopper 92 are illustrated as comprising foursidewalls which converge to elongated rectangular shaped bottom sections99 and 100, respectively. Solids feeder systems 101 and 102 areoperatively positioned within each bottom section 99 and of sand hopper91 and rock hopper 92, respectively. Air blower 103 is positioned underrock hopper 92 and carries an air inlet 104 and air delivery conduit 105which operatively communicates from the outlet of air blower 103 throughsolids feeder unit 102, conduit 114, solids feeder unit 101, conduit115, and cement receiving manifold 98 to air-solids manifold 106.

Solids feeder units 101 and 102 have the same basic components andfunction basically in an identical manner and will be describedspecifically in relation to solids feeder unit 102, as illustrated inFIG. 8. The identical components of solids feeder units 101 and 102 areidentified by the same arabic character-expect those of solids feederunit 101 are followed by the letter a. As illustrated, solids feederunit 102 comprises shroud 107, which is a housing positioned aroundendless belt 108 which in turn is movably mounted over roller 109 and110. Endless belt 108 carries a series of upright cleats 111, eachcarrying a resilient lockingportion 112 on the tip thereof, which makessealing contact between endless belt 108 and shroud 107. As shown,shroud 107 extends completely around endless belt 108, making sealingcontact with resilient locking portions 112 of each upright cleat 111.In addition, extensions 113 of shroud 107 extend inwardly into hopper92, a short distance at the points wherein endless belt 108 enters andexits from bottom section 100 thereof.

Air delivery conduit 105 operatively communicates through the lowermiddle sidewall of shroud 107 at a point between the lower returningportion 108L of endless belt 108 and bottom section of shroud 107. Asshown in FIGS. 9 and 10, conduit 114 communicates between shroud 107 ofsolids feeder unit 102 and shroud 107a of solids feeder unit 101opposite the point that air delivery conduit 105 communicates withshroud 107. Thus, conduit 114 communicates with shroud 107a in exactlythe same manner that air delivery conduit 105 communicates with shroud107. In this manner an air flow path is provided from air deliveryconduit 105 through the lower middle sidewalls of shroud 107 to thelower middle sidewall portionof shroud 107a via conduit 114. Againreferring to FIGS. 9 and 10, conduit 115 communicates from the lowermiddle sidewall of shroud 107a at a point opposite the place ofconnection of conduit 114 to cement receiving manifold 98. Therefore, aflow path is provided from air delivery conduit 105 through the lowermiddle sidewall portion of shroud 107 below the lower portion 1081.. ofendless belt 108 and into conduit 114, from conduit 114 through thelower portion of shroud 107a and under the lower portion 108L of endlessbelt 108a contained therein, from shroud 107a to conduit 115, and fromconduit 115 through cement receiving manifold 98 to air solids manifold106.

Now referring to FIGS. 8-10, the power connections to the solids feederunits 101 and 102, air blower 103 and the water supply unit in truck 70will be explained in detail. As shown, transfer case 116 from driveshaft 117 of engine 130 operatively communicates to differential joint 118 for providing power to the rear wheels of vehicle 70, and also to airblower 103 via drive shaft 120. Air blower 103 can be any conventionalblower mechanism which is powered by drive shaft 120 and is illustrated(in broken line) as a Rootes type blower 121 rotatably mounted withinthe housing forming the exterior of air blower 103. Transfer case 116 isattached to a conventional control mechanism for controlling theengagement and disengagement of driveshaft 120 to the power train.

In addition, conventional power takeoff unit 122, f example a hydraulicpower take-off unit, is attached to driveshaft 1 17 from the engine 130.Power take-off unit 122 can be any conventional power take-off unit suchas for example the one manufactured by Spicer Corp. Power take-off unit122 provides rotating power to a spindle 123 which in turn drivespulleys (timing pulleys) 124 and 125. Timing pulley 124 carries a seriesof four timing belts 150 which in turn drive pulley 126, which isoperatively attached through clutch 127 to the power system for solidsfeeder units 101, 102 and cement feeder unit 95. Clutch 127 is anyconventional clutch unit which is adapted to be operated by the driverof vehicle 70. Spindle 128 from clutch 127 communicates to right anglegear box 129. Right angle gear box 129 carries a suitable right anglegear mechanism such as a pair of miter gears which transfer rotatingpower to feeder drive shaft 131. Feeder drive shaft 131 directly drivesroller 109 which functions to drive endless belt 108 and in turncommunicates through variable speed drive mechanism 132 which operatesto drive roller 109a, which in turn drives endless belt 108a. Variablespeed drive mechanism 132 can comprise any conventional drive mechanismsuch as manufactured by Link Belt Corp. under the tradename PIV andfunctions to rotate shaft 133 for drive roller 109a of endless belt108a. Feeder drive shaft 131 which passes through variable speed drivemechanism 132 functions to operate variable speed drive mechanism 134for cement feeder 95. Variable speed drive mechanism 134 can be anyconventional variable speed mechanism such as variable speed drivemechanism 132 and functions to drive sprocket 135 at a suitable speed.Sprockets 135 drives chain 136, which in turn communicates over sprocket137 of cement feeder and functions to rotate the feeder vanes 96therewithin.

In addition to driving timing pulley 124, spindle 123 of power take-offunit 122 also drives timing pulley 125 which drives timing belts 151that pass over pulley 138 of water pump 139. Water pump 139 communicateswith water tank 93 via conduit 140 and with water delivery conduit 17via conduit 141.

In operation of truck 70, with the engine 130 running, extendable boom71 is adjusted in a conventional manner so that concrete mixing anddelivery unit 12 can be positioned with its outlet 18 directly over adesired concrete placement point. Next, transfer case 116 is engaged sothat driveshaft to air blower 103 is energized, thereby causing acontinuous stream of air to pass from air conduit 105 through the lowerportion of shroud 107, conduit 114, the lower portion of shroud 107a,conduit 115, cement receiving manifold 98, and air solids manifoldconduit 106 to delivery conduit 10 operatively communicated thereto.Next, power take-off unit 122 is engaged to thereby impart rotatingmotion to pulleys 124 and which in turn impart rotating motion to pulley126 and pulley 138 which drives water pump 139. The actuation of clutch127 rotates solids feeder drive shaft 131, and causes the rotation ofroller 109 and the subsequent movement of endless belt 108 carryingcelats 111 across the bottom of rock hopper 92. Similarly, driveshaft133 is energized causing the rotation of roller 109a and thesubsebetween adjacent cleats 111 and pass them through shroud 107 intoconduit 114. In similar manner, sand is entrapped between cleats 111a asthey pass across the bottom of hopper 91 and under shroud 107a. The aircontaining the entrained rocks passes from conduit 114 through adjacentcelats 111a within shroud 107a and entrains the sand therewithin toyield an air-sandrock stream which is delivered to conduit 115. Thevanes 96 of cement feeder 95 deposit the requisite amount of the dryPortland cement into the cement receiving manifold 98. This cement isentrained in the air-sand-rock stream to form a combined air-solidsstream which is delivered into air-solids manifold conduit 106 which inturn delivers the mixture to fluidsolids conduit 10 which operativelycommunicates with concrete mixing and delivery unit 12 as explained indetail in FIGS. 1-6. The rotation of endless belts 108 and 108a and therotation of vanes 96 within cement feeder 95 are synchronized such thata suitable ratio of rock-to-sand-to-cement is delivered through theairstream passing to conduit 10. A suitable such ratio with an airvelocity of from 75 to 200 feet per second includes a weight ratio ofcement-to-sand-to-rock for example of about l:3:3.7. The composition ofthe concrete mixture being delivered is adjusted by varying the speed ofthe sand and cement and water feeder systems with respect to the rocksystem. It is well understood that one skilled in the art can alter theratio between air, cement and aggregate in any suitable manner toprovide the desired cementitious mix.

Simultaneously, actuation of water pump 139 by timing belts 151 resultsin water flow passing from conduit 140 to conduit 141, which is incommunication-with water delivery conduit 17. Water delivery conduit 17in turn delivers suitable amounts of water to water injector 16 whichuniformly injects water into the fluidsolids stream flowing throughconduit 10. With the weight ratios as set forth above, water can beinjected into such stream in amounts as required to produce the desiredconcrete consistency. The fluid-solids stream passingfrom water injector16 is passed into the inlet of concrete mixing and delivery unit 12 in amanner as described above in relation to FIGS. l-6. The stream isdecelerated and thoroughly mixedjwithin unit 12 and is allowed to dropfrom'the outlet 18 thereof upon the predetermined concrete placementpoint.

While this invention has been described in relation to its preferredembodiments, it is to be understood that various modifications thereofwill now be apparent to one skilled in the art upon reading thisspecification, and it is intended to cover such modifications as fallwithin the scope of the appended claims.

We claim:

1. A method of delivering a cementitious material to a placement pointcomprising:

a. entraining a mixture of water, cement and aggregate in a gas stream;

b. introducing said gas stream carrying said mixture tangentially intoand enclosed, deceleration and mixing zone having an outlet positionedover said placement point to cause said mixture to rotate downwardlytoward said outlet in a spiral path in said deceleration and mixing zonethereby thoroughly blending and decelerating said mixture to form saidcementitious material; and

0. allowing said cementitious material to drop from said opening uponsaid placement point.

2. The method of claim 1 wherein said mixture is decelerated to thegravitational velocity thereof.

. 3. The method of delivering a mixture of cementitious material to aplacement point comprising:

a. entraining a settable material comprising a hydratable cement in agas stream;

b. passing said gas stream containing said material through a wateraddition zone wherein sufficient water is added thereto to causehydration of said cement;

c. introducing said gas stream carrying the resulting mixture of waterand cement material tangentially into an enclosed deceleration andmixing zone having an outlet positioned over said placement point tocause said mixture to rotate downwardly in a spiral path in said zonetoward said outlet thereby thoroughly blending and decelerating saidmixture and forming said mixture of cementitious material; and

d. allowing said mixture of cementitious material to drop from saidoutlet upon said placement point.

4. The method of claim 3 wherein said mixture is decelerated to thegravitational velocity thereof.

5. A method of delivering a mixture of cementitious material includingwater and a hydratable cement as two ingredients thereof to a placementpoint comprising:

a. entraining one of said ingredients in a gas stream;

b. passing said gas stream to an injection zone wherein the other ofsaid two ingredients is added thereto, and thereby forming a mixture ofsaid two ingredients entrained within said gas stream;

c. introducing said gas stream carrying said mixture tangentially intoan enclosed deceleration and mixing zone having an outlet positionedover said placement point to cause said mixture to rotate downwardly ina spiral path in said zone toward said outlet thereby thoroughlyblending and decelerating said mixture and forming said mixture tocementitious material; and

d. allowingsaid cementitious material to drop from said opening uponsaid placement point.

' 6. The method of claim 5 wherein the first ingredient which is addedto said gas stream is said hydratable cement and the second ingredientwhich is added to said gas stream is water.

7. The method of claim 5 further comprising entraining aggregate intosaid gas stream prior to passing said stream into said encloseddeceleration and mixing zone.

8. A method of delivering a mixture of cementitious material includingwater and a hydratable cement as two ingredients thereof to a placementpoint comprismg:

a. entraining one of said ingredients in a gas stream;

b. passing said gas stream to an injection zone wherein the other ofsaid two ingredients is added thereto, and thereby forming a mixture ofsaid two ingredients entrained within said gas stream;

c. introducing said gas stream carrying said mixture transversely .intoa vertically elongated enclosed deceleration and mixing zone having anoutlet positioned over said placement pointand imparting rotating motionto said mixture thereby causing it to rotate and move downwardly in aspiral path within said zone toward said outlet, thereby blending andtable cement.

10. The method of claim 8 further comprising entraining aggregate intosaid gas stream prior to introducing said stream into said encloseddeceleration and mixing zone.

1. A method of delivering a cementitious material to a placement pointcomprising: a. entraining a mixture of water, cement and aggregate in agas stream; b. introducing said gas stream carrying said mixturetangentially into and enclosed, deceleration and mixing zone having anoutlet positioned over said placement point to cause said mixture torotate downwardly toward said outlet in a spiral path in saiddeceleration and mixing zone thereby thoroughly blending anddecelerating said mixture to form said cementitious material; and c.allowing said cementitious material to drop from said opening upon saidplacement point.
 2. The method of claim 1 wherein said mixture isdecelerated to the gravitational velocity thereof.
 3. The method ofdelivering a mixture of cementitious material to a placement pointcomprising: a. entraining a settable material comprising a hydratablecement in a gas stream; b. passing said gas stream containing saidmaterial through a water addition zone wherein sufficient water is addedthereto to cause hydration of said cement; c. introducing said gasstream carrying the resulting mixture of water and cement materialtangentially into an enclosed deceleration and mixing zone having anoutlet positioned over said placement point to cause said mixture torotate downwardly in a spiral path in said zone toward said outletthereby thoroughly blending and decelerating said mixture and formingsaid mixture of cementitious material; and d. allowing said mixture ofcementitious material to drop from said outlet upon said placementpoint.
 4. The method of claim 3 wherein said mixture is decelerated tothe gravitational velocity thereof.
 5. A method of delivering a mixtureof cementitious material including water and a hydratable cement as twoingredients thereof to a placement point comprising: a. entraining oneof said ingredients in a gas stream; b. passing said gas stream to aninjection zone wherein the other of said two ingredients is addedthereto, and thereby forming a mixture of said two ingredients entrainedwithin said gas stream; c. introducing said gas stream carrying saidmixture tangentially into an enclosed deceleration and mixing zonehaving an outlet positioned over said placement point to cause saidmixture to rotate downwardly in a spiral path in said zone toward saidoutlet thereby thoroughly blending and decelerating said mixture andforming said mixture to cementitious material; and d. allowing saidcementitious material to drop from said opening upon said placementpoint.
 6. The method of claim 5 wherein the first ingredient which isadded to said gas stream is said hydratable cement and the secondingredient which is added to said gas stream is water.
 7. The method ofclaim 5 further comprising entraining aggregate into said gas streamprior to passing said stream into said enclosed deceleration and mixingzone.
 8. A method of delivering a mixture of cementitious materialincluding water and a hydratable cement as two ingredients thereof to aplacement point comprising: a. entraining one of said ingredients in agas stream; b. passing said gas stream to an injection zone wherein theother of said two ingredients is added thereto, and thereby forming amixture of said two ingredients entrained within said gas stream; c.introducing said gas stream carrying said mixture transversely into avertically elongated enclosed deceleration and mixing zone having anoutlet positioned over said placement point and imparting rotatingmotion to said mixture thereby causing it to rotate and move downwardlyin a spiral path within said zone toward said outlet, thereby blendingand decelerating said mixture and forming said mixture of cementitiousmaterial; and d. allowing said cementitious material to drop from saidopening upon said placement point.
 9. The method of claim 8 wherein thefirst of said two ingredients which is added to said gas stream ishydratable cement.
 10. The method of claim 8 further comprisingentraining aggregate into said gas stream prior to introducing saidstream into said enclosed deceleration and mixing zone.